The present invention relates generally to a sound reproducing device and sound reproducing method by which compressed sound waveform data is transferred and a receiving end decodes and audibly reproduces the sound waveform data. More particularly, the present invention relates to a sound reproducing device and sound reproducing method which use different sound-waveform-data compressing techniques between a case where a sound needs to be generated in real time and a case where a sound need not be generated in real time.
The present invention also relates to a sound reproducing technique for use in karaoke or the like which is characterized by an improved data compressing technique to compress sampled sound or sound waveform data for subsequent storage.
The present invention also relates to a sound reproducing technique for use in karaoke or the like which allows any one or more of different data compressing techniques to be selectively employed when sampled sound or sound waveform data is to be used in compressed data form.
The present invention also relates to a game device which is capable of providing a sound or waveform data, to be audibly reproduced in accordance with progression of a game program, in compressed data form.
Among a variety of conventionally known music reproducing devices are "karaoke" devices. The karaoke device, in its simplest form, used to reproduce a selected music piece from a magnetic tape that has prerecorded thereon the music piece in the form of analog signals. However, with the developments in electronic technology, magnetic tapes have almost been replaced by CDs (Compact Disks) or LDs (Laser Disks), so that analog signals to be recorded thereon have been replaced by digital signals and data to be recorded with the digital signals have come to include various additional information, such as image data and lyrics data, accompanying the fundamental music piece data.
Recently, in place of CDs or LDs, communication-type karaoke devices have come to be widely used at a rapid speed. Such communication-type karaoke devices may be generally classified into two types: the non-accumulating type where a set of data on a music piece (i.e., music piece data) to be reproduced is received via a communication line each time the music piece is selected for reproduction; and the accumulating type where each set of music piece data received via the communication line is accumulatively stored in an internal storage device (hard disk device) of the karaoke device in such a manner that a particular one of the accumulated sets of music piece data is read out from the storage device each time it is selected. At present, the accumulating type karaoke devices are more popular than the non-accumulating type karaoke devices in terms of the communicating cost.
In most of these communication-type karaoke devices, there are employed latest or newest data compressing and communicating techniques with a view to minimizing a total data quantity of music piece data per music piece to thereby achieve a minimized communicating time (and hence communicating cost) and minimized necessary storage space. In other words, the communication-type karaoke devices are not satisfactory in terms of the required communicating cost and communicating time if they use conventional PCM data (i.e., data obtained by sampling the whole of a music piece) exactly the way they are recorded on a CD or LD. Thus, in the conventional communication-type karaoke devices, performance-related data, contained in the music piece data, are converted or coded into data conforming to the MIDI (Musical Instrument Digital Interface) standards (hereinafter referred to as "MIDI data"), and also human voice sounds as in a back chorus, which are difficult to code into MIDI data, are PCM-coded to be expressed in a data-compressed code form. Typically, an ADPCM (Adaptive Differential Pulse Code Modulation) form has been conventionally used as the data-compressed code form. This can reduce a total data quantity of music piece data per music piece, to thereby effectively save communicating time and storage capacity.
Although in the compressed data form, the ADPCM data are still far greater in total data quantity than the MIDI data and thus would occupy a great part (about two-thirds) of the available storage capacity in the karaoke device, which has been one of the main factors that limit the number of music piece data accumulable in the storage device of the karaoke device. This would also considerably limit a reduction in the time and cost necessary for communication of the music piece data.
Further, conventionally-known electronic game devices are designed to allow a game to progress and perform music, visually display images and audibly generate sounds (such as human voices and effect sounds) in accordance with the progression of the game, by sequentially executing a program for the body of the game and also sequentially reading out additional data, such as BGM (Background Music) data, image data and sound data, relating to the game.
However, with game devices equipped with no CD-ROM drive, i.e., game devices of a type where a ROM cartridge is removably attached, the game program and minimally necessary additional data must be pre-written in the ROM, which are absolutely essential to the progression of the game and can never be abridged. The BGM data, which are formed of data conforming to the MIDI standards, do not require a great storage space, and hence abridging the BGM data would not substantially save storage capacity. In contrast, the sound data are less frequently used in the progressing game and can be replaced by character data for visual display as character images, although they are greater in total data quantity than the BGM data; thus, the sound data may often be partly abridged without adversely influencing the progression of the game.
Therefore, in today's game devices and the like using such a ROM cartridge, the minimally necessary sound data are stored into a limited area of the cartridge only after the essential game program, image data and BGM data have been written in the cartridge. So, in the game devices of the type where the sound data are stored in such a ROM cartridge, the ADPCM technique is employed, as a means to compress the sound data, in order to minimize a necessary storage space for the sound data. This data compressing technique permits a significant reduction in the total data quantity of the sound data, so that the sound data can be stored in the ROM cartridge or the like in sufficient quantities to highly enhance musical effects during the progression of the game.
However, with recent game software, the program for the game body and image data are getting increasingly large in size, which would inevitably limit the storage area, in the ROM cartridge, to be used for the BGM data and sound data. Thus, the ADPCM data, which, although in compressed data form, are much greater in total data quantity that the MIDI data, have to be further abridged by being converted into character data, with the result that only the minimally necessary sound data can be stored in the ROM cartridge. This would present the problem that a total quantity of the sound data storable in the ROM cartridge can not be significantly increased even though the sound data are compressed by the ADPCM compressing technique.